Chromium-free corrosion preventive and corrosion prevention method

ABSTRACT

A chromium-free corrosion inhibitor containing at least one titanium, silicon and/or zirconium compound corresponding to general formula (I): 
                         
in which Me is a titanium, silicon or zirconium ion, at least one other olefinically unsaturated comonomer containing at least two olefinically unsaturated double bonds per molecule, optionally other comonomers containing one olefinically unsaturated double bond per molecule, and at least one radical and/or cationic polymerization initiator that is activated by radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage application filed under 35U.S.C. § 371 of International Application No. PCT/EP00/04151, filed May10, 2000, in the European Patent Office, claiming priority under 35U.S.C. §§ 119 and 365 of PCT/EP00/04151 and DE 199 23 118.4, filed onMay 19, 1999, in the German Patent Office.

This invention relates to a chromium-free organic/organometalliccorrosion inhibitor and to a corrosion-inhibiting process for thetreatment of surfaces of steel—optionally provided with a metalliccoating of zinc, aluminium, copper, nickel, etc.—or of aluminium and itsalloys. It is particularly suitable for surface treatment in coilcoating plants for the use of these substrates in the domestic andarchitectural sectors and in the automotive industry.

For temporary protection against corrosion, galvanized oralloy-galvanized steel strip is either simply coated withcorrosion-inhibiting oils or—where there is a more serious risk ofcorrosion—is phosphated or chromated. The final coating step usingorganic binders (primers, paints) is generally preceded by a multistageprocess. For the use of galvanized metal strip or aluminium and itsalloys in the domestic appliance and architectural industries, the metalsurface is first provided with a corrosion-inhibiting layer, optionallyafter removal of the oil layer. The best known anti-corrosion measure ischromating where the metal surface is coated with a chromium(III) and/orchromium(VI)-containing layer generally containing about 5 to 15 mg/m²chromium. Phosphating as an alternative temporary anti-corrosion measurehas two disadvantages: first, the appearance of the metal surfaces canbe undesirably altered and, second, phosphating is equipment-intensivebecause—depending on the substrate material—it involves an additionalactivation step and generally a post-phosphating passivation step.Besides the actual protection against corrosion, the inorganic coatingensures good adhesion to the primer applied thereto. The primer in turnnot only favorably influences the corrosion-inhibiting effect of theinorganic conversion layer, it also provides the finishing paint with agood adhesion base.

Metal plates are also being increasingly supplied by the finisher with abase coat which, for example, facilitates such machining operations asstamping, drilling, grooving, profiling and/or deep drawing. Besidescorrosion-inhibiting properties, this base coat is also expected to makethe plate easier to machine. Another function of such base coats is toestablish an adhesion base for following aesthetic surface coatings. Aworkpiece made from correspondingly pretreated plate material bymachining may then be coated with a finshing paint in a concluding step.The base coat according to the invention also preferably serves as aprimer, in which case surface coating is carried out immediatelyafterwards in the coil coater. In this case, only the fully coated platematerial is subjected to further processing. It is known that coilcoating consists essentially of three steps. In the first step, themetal strip is cleaned and provided with an (inorganic) pretreatmentlayer; in the second step, the primer is applied and, in the concludingthird step, the finishing paint is applied. In some applications,varnish or protective film coatings may also be applied. Attempts havealready been made to use the pretreatment step for the functionsperformed by the base coat described above. To this end, a suitableorganic polymer capable of forming a surface film with the functionalproperties demanded of a base coat is added, for example, in theinorganic conversion treatment.

U.S. Pat. No. 5,344,504, for example, describes a process for coatinggalvanized steel in which the substrate is coated with a treatmentsolution having the following composition: 0.1 to 10 g/l of a tetra- orhexafluoro acid of boron, silicon, titanium and zirconium orhydrofluoric acid, ca. 0.015 to ca. 6 g/l cations of cobalt, copper,iron, manganese, nickel, strontium or zinc and optionally up to about 3g/l of a polymer selected from polyacrylic acid, polymethacrylic acidand esters thereof. The pH value of this treatment solution is in therange from about 4 to about 5.

WO 95/14117 also describes a process for treating surfaces of zinc oraluminium or alloys thereof. In this process, the surfaces are contactedwith a treatment solution having a pH below 3 which contains a complexbetween a metal oxo-ion and a hetero-ion. The metal oxo-ion is selectedfrom molybdate, tungstate and vanadate. The hetero-ion is selected fromphosphorus, aluminium, silicon, manganese, magnesium, zirconium,titanium, tin, cerium and nickel. The treatment solution also containsan inorganic film former which is compatible with the other componentsof the solution. Suitable film formers are, for example, polyacrylatessuch as, in particular, polymers of methyl methacrylate, n-butylacrylate, hydroxyethyl acrylate and glycerol propoxytriacrylate.

EP-A-694 593 recommends treating the metal surfaces with a treatmentsolution containing the following components: an organic polymer orcopolymer where 0.5 to 8% of the monomers bear groups capable of formingcompounds with metal ions, complex cations or anions of aluminium,calcium, cerium, cobalt, molybdenum, silicon, vanadium, zirconium,titanium, trivalent chromium and zinc, an oxidizing agent, such asnitric acid, perchloric acid or hydrogen peroxide, and an acid such as,for example, oxalic acid, acetic acid, boric acid, phosphoric acid,sulfuric acid, nitric acid or hydrochloric acid.

WO 95/04169 teaches the treatment of metal surfaces with a treatmentsolution containing at least one of the following components:fluorocomplexes of titanium, zirconium, hafnium, silicon, aluminium andboron, metal ions selected from cobalt, magnesium, manganese, zinc,nickel, tin, copper, zirconium, iron and strontium, phosphates orphosphonates and water-soluble or water-dispersible organic filmformers.

EP-A-792 922 describes a chromium-free corrosion-inhibiting coatingcomposition for aluminium or aluminium alloys which contains afilm-forming organic polymer and (i) a salt selected from esters of rareearth metals, alkali metal or alkaline earth metal vanadate and (ii) aborate salt of an alkaline earth metal. Preferred polymers mentionedinclude, for example, epoxides, including polyimide-based epoxides,polyurethanes, acrylic polymers and alkyd-based systems. Accordingly,this coating composition must contain at least one borate and one othercomponent which may be a vanadate in addition to the organic filmformer.

EP-A-685 534 describes a process for protecting a steel substrate by athin film of an organic/inorganic hybrid polymer based on analkoxysilane, another condensible organometallic compound with theformula M(OR)₄ and (meth)acrylic acid, water and a polymerizationinitiator. The coating is formed by thermal or photopolymerization.Zirconium and titanium are mentioned as metals for the organometalliccompound. It is stated that the film in question protects steelsubstrates against corrosion and oxidation. In addition, the coating issaid to protect the substrate against shock and other mechanicaleffects.

WO 98/47631 describes a process for the remedial treatment ofdefectively pretreated metal surfaces. To this end, the defective metalsurfaces are coated with an aqueous acidic solution containingfluorometallate anions, divalent or trivalent cations of cobalt,magnesium, manganese, zinc, nickel, tin, copper, zirconium, iron andstrontium; phosphorus-containing inorganic oxo anions and phosphonateanions and a water-soluble and/or water-dispersible organic polymerand/or a polymer-forming resin. The document in question does notindicate whether the compositions in question are also suitable for thefirst-time treatment of non-precoated metal strip.

Hitherto unpublished DE-A-197 54 108.9 describes a chromium-freewater-based corrosion inhibitor for the treatment of surfaces ofgalvanized or alloy-galvanized steel and of aluminium. It contains askey components hexafluoro anions of titanium and/or zirconium, vanadiumions, cobalt ions, phosphoric acid and preferably an organic, moreparticularly polyacrylate-based, film former. This corrosion inhibitoris particularly suitable for the anti-corrosion treatment of metalstrip.

Hitherto unpublished DE 197 51 153.8 describes polymerizablechromium-free organic compositions containing titanium, manganese and/orzirconium salts of olefinically unsaturated polymerizable carboxylicacids and other olefinically unsaturated comonomers and a radicalpolymerization initiator and their use for the organic coil coating ofmetallic materials. Although these nonaqueous polymerizable compositionsallow the chromium-free pretreatment of steels with corrosion-inhibitingproperties, these corrosion-inhibiting properties are in need ofimprovement for many applications.

Despite the extensive prior art, there is still a need for improvedcorrosion inhibitors and coating processes for metal surfaces whichwould provide for the chromium-free pretreatment of the metal substratesand for effective corrosion prevention without the use of acids or highfluoride levels. The constituents would preferably be homogeneouslydissolved or dispersed in the composition to avoid separation duringproduction. transportation, storage and use.

The coating would facilitate the stamping and forming of the workpiecesfrom the coated metal strip. In addition, the layers of the metalsubstrates would withstand the other fabrication steps up to assembly ofthe products such as, for example, cleaning, optionally phosphating,riveting, welding and would lend themselves to coating with a finishingpaint either directly or after machining. In the interests of pollutioncontrol and works safety, the treatment process would be able to becarried out without the use of chromium compounds and in the absence oforganic solvents. The principal fields of application would be thedomestic appliance and architectural industries mentioned above.

DESCRIPTION OF THE INVENTION

The solution to the problem as provided by the present invention isdefined in the claims and consists essentially in the provision of achromium-free corrosion inhibitor containing:

-   -   at least one titanium, silicon and/or zirconium compound        corresponding to general formula (I):

-   -   in which R¹ and/or R² represent H, C₁₋₁₂ alkyl, aralkyl or the        group —CO—O—Y,    -   R³ is H or C₁₋₁₂ alkyl,    -   Me is a titanium, silicon or zirconium ion,    -   X is H, C₁₋₁₂ alkyl, aryl or aralkyl, alkoxyl, aroxyl, sulfonyl,        phosphate, pyrophosphate,    -   Y is H, C₁₋₁₂ alkyl or Me and    -   n=0 to 4,    -   at least one other olefinically unsaturated comonomer containing        at least two olefinically unsaturated double bonds per molecule,    -   optionally other comonomers containing one olefinically        unsaturated double bond per molecule,    -   at least one radical and/or cationic polymerization initiator.

In a preferred embodiment, the corrosion inhibitor contains noadditional solvent. All the ingredients of the corrosion inhibitorshould react off completely in the course of the process describedhereinafter and should remain in the coating to be produced.

The present invention also relates to a process for thecorrosion-inhibiting treatment of steel—optionally provided with ametallic coating of zinc, aluminium, copper, nickel or similar metals—oraluminium or its alloys which comprises the following key process steps:

-   a) contacting the surface of the substrate with a corrosion    inhibitor of the above-mentioned type for 0.5 to 60 seconds at a    treatment temperature of 10 to 50° C. and preferably in the range    from 15 to 35° C.,-   b) removing the excess corrosion inhibitor, if any, from the surface    and-   c) crosslinking the polymeric film and anchoring it on the metal    surface by suitable supply of energy for 0.1 to 120 seconds.

In a preferred embodiment, the corrosion inhibitor is applied to thesurface of the workpiece, preferably metal strip, by flooding/squeezing,spraying/squeezing, film application (for example by the curtain flowprocess), suitable stripper or roller applications.

Specific examples of the titanium, silicon and/or zirconium compounds offormula (I) to be used in accordance with the invention are isopropyldimethacrylisostearoyl titanate, isopropyl tri(dodecyl)-benzenesulfonyltitanate, isopropyl tri(octyl)phosphatotitanate, isopropyl(4-amino)benzenesulfonyl-di-(dodecyl)benzenesulfonyl titanate, alkoxyltrimethacryltitanate, isopropyl tri(dioctyl)pyrophosphatotitanate,alkoxy triacryltitanate, isopropyl tri(N-ethylenediamino)ethyl titanate,di(cumyl)phenyl oxoethylene titanate, di(dioctyl)pyrophosphateoxoethylene titanate, dimethyl oxoethylene titanate,di(butylmethyl)pyrophosphate oxoethylene di(dioctyl)phosphitotitanate,di(dioctyl)phosphatoethylene titanate,di(butylmethyl)pyrophosphatoethylene titanate, tetraethyl titanate,tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyltitanate, n-butyl polytitanate, tetra-2-ethylhexyl titanate,tetraisooctyl titanate, isostearoyl titanate, monomeric cresyl titanate,polymeric cresyl titanate, octyleneglycol titanate, titanyl acetylacetonate, diisopropoxy-bis-ethyl acetoacetatotitanate,di-n-butoxy-bis-ethyl acetoacetatotitanate, diisobutoxy-bis-ethylacetoacetatotitanate, triethanolamine titanate, isopropyl triisostearoyltitanate, adducts of 2-(N,N-dimethylamino)isobutanol, triethyl amine,(meth)acrylate-functionalized amine derivative,methacrylamide-functionalized amine derivative withdi(dioctyl)phosphatoethylenetitanate, tetraisopropyldi(dioctyl)phosphitotitanate, tetraoctyldi(ditridecyl)phosphitotitanate, tetra-(2,2-diallyloxymethyl)butyldi(ditridecyl)phosphitotitanate, neopentyl (diallyl)oxytrineodecanoyltitanate, neopentyl (diallyl)oxytri(dodecyl)benzenesulfonyl titanate,neopentyl (diallyl)oxytri(dioctyl)phosphatotitanate, neopentyl(diallyl)oxytri(dioctyl)pyrophosphatotitanate, neopentyl(diallyl)oxytri(N-ethylenediamino)ethyl titanate, neopentyl(diallyl)oxytri(m-amino)phenyl titanate, neopentyl(diallyl)oxytrihydroxycaproyl titanate,cyclo(dioctyl)pyrophosphatodioctyl titanate,dicyclo(dioctyl)pyrophosphatotitanate, 2-(acryloxyethoxy)-trimethylsilane, N-(3-acryloxy-2-hydroxypropyl)-3-aminopropyl triethoxysilane,(3-acryloxypropyl)dimethylmethoxysilane,(3-acryloxypropyl)methylbis(trimethylsiloxy)silane,(3-acryloxypropyl)methyl dimethoxysilane,(3-acryloxypropyl)trimethoxysilane,(3-acryloxypropyl)tris(trimethylsiloxy)-silane, acryloxytrimethylsilane,1,3-bis((acryloxymethyl)phenethyl)-tetramethyl disiloxane,bis(methacryloxy)diphenylsilane,1,3-bis(3-methacryloxypropyl)tetrakis(trimethylsiloxy)disiloxane,1,3-bis(3-methacryloxypropyl)tetramethyldisiloxane,1,3-bis(methacryloxy)-2-trimethylsiloxypropane, methacrylamidopropyltriethoxysilane, methacrylamidotrimethylsilane,methacryloxyethoxytrimethylsilane,N-(3-methacryloxy-2-hydroxypropyl)-3-aminopropyl triethoxysilane,(methacryloxymethyl)bis(trimethylsiloxy)methylsilane,(methacryloxymethyl)dimethylethoxysilane,(methacryloxymethyl)phenyldimethylsilane,methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane,methacryloxymethyltrimethylsilane,methacryloxymethyltris(trimethylsiloxy)silane,O-methacryloxy(polyethyleneoxy)trimethylsilane, 3-methacryloxypropylbis(trimethylsiloxy)methylsilane, 3-methacryloxypropyldimethylethoxysilane, methacryloxypropyl dimethylmethoxysilane,methacryloxypropyl methyl diethoxysilane, methacryloxypropyl methyldimethoxysilane, methacryloxypropyl pentamethyldisiloxane,methacryloxypropylsilatrane, methacryloxypropyl triethoxysilane,methacryloxypropyl trimethoxysilane, methacryloxypropyltris(methoxyethoxy)silane, methacryloxypropyltris(trimethylsiloxy)silane, methacryloxypropyltris(trimethylsiloxy)silane, methacryloxypropyltris(vinyldimethylsiloxy)silane, methacryloxy trimethylsilane,tetrakis(2-methacryloxyethoxy)silane, Zr-hexafluoropentanedionate,Zr-isopropoxide, Zr-methacryloylethyl acetoacetate tri-n-propoxide,Zr-2-methyl-2-butoxide, Zr-2,4-pentanedionate, Zr-n-propoxide,Zr-2,2,6,6-tetramethyl-3,5-heptanedionate, Zr-trifluoropentanedionate,Zr-trimethylsiloxide, dicyclopentadienyl zirconium diethoxide,Zr-2-ethyl hexanoate, Zr-methacrylate, Zr-dimethacrylate.

Suitable comonomers containing at least two olefinically unsaturateddouble bonds per molecule are any of a number of comonomers, for exampleesterification products of alkane polyols, polyester polyols, polyetherpolyols or polyepoxides optionally containing hydroxyl groups witholefinically unsaturated carboxylic acids such as, for example, acrylicacid, methacrylic acid, itaconic acid, crotonic acid, maleic acid,maleic acid semiester, fumaric acid, fumaric acid semiester or reactivecarboxyfunctional macromonomers or mixtures thereof. Other suitablecomonomers containing at least two reactive double bonds per moleculeare (meth)acrylate-functional polysiloxanes, (meth)acrylate-functionalaliphatic, cycloaliphatic and/or aromatic polyepoxides and polyurethanecompounds containing reactive (meth)acrylate groups. The above-mentionedcomonomers containing at least two olefinically unsaturated double bondsper molecule typically have molecular weights in the range from 600 to50,000 and preferably in the range from 1,000 to 10,000.

Specific examples of alkane polyols are butane-1,4-diol,hexane-1,6-diol, octane-1,8-diol and higher homologs thereof, glycerol,trimethylol propane, pentaerythritol and alkoxylation products thereof.

Besides the above-mentioned alkane polyols, suitable polyols are liquidpolyhydroxy compounds containing two or three hydroxyl groups permolecule such as, for example, di- and/or trifunctional polypropyleneglycols with molecular weights in the range from 200 to 6,000 andpreferably in the range from 400 to 3,000. Statistical and/or blockcopolymers of ethylene oxide and propylene oxide may also be used.Another group of preferred polyethers are the polytetramethylene glycolswhich may be produced, for example, by the acidic polymerization oftetrahydrofuran. The molecular weights of the polytetramethylene glycolsare in the range from 200 to 6,000 and preferably in the range from 400to 4,000.

Other suitable polyols are the liquid polyesters obtainable bycondensation of di- or tricarboxylic acids such as, for example, adipicacid, sebacic acid, glutaric acid, azelaic acid, suberic acid,3,3-dimethylglutaric acid, terephthalic acid, isophthalic acid,hexahydrophthalic acid or dimer fatty acid with low molecular weightdiols or triols such as, for example, ethylene glycol, propylene glycol,diethylene glycol, triethylene glycol, dipropylene glycol,butane-1,4-diol, hexane-1,6-diol, decane-1,10-diol, dimer fatty alcohol,glycerol or trimethylolpropane. Another group of polyol componentssuitable for use in accordance with the invention are the polyestersbased on ε-caprolactone which are also known as polycaprolactones.However, polyesterpolyols of oleochemical origin may also be used.Polyester polyols such as these may be produced, for example, bycomplete ring opening of epoxidized triglycerides of a fattymixture—containing at least partly olefinically unsaturated fattyacids—with one or more alcohols containing 1 to 12 carbon atoms andsubsequent partial transesterification of the triglyceride derivativesto form alkyl ester polyols containing 1 to 12 carbon atoms in the alkylmoiety. Other suitable polyols are polycarbonate polyols and dimer diols(Henkel) and castor oil and its derivatives. The hydroxyfunctionalpolybutadienes commercially obtainable, for example, as “Poly-bd” mayalso be used as polyols for the compositions according to the invention.

Also suitable for the purposes of the present invention are one or moreradical-polymerizable polyurethane compounds (A), (B) and/or (C)corresponding to general formula (II):(H₂C═CR¹—C(═O)—O—R²—O—C(═O)—NH—)_(n)R³  (II)in whichR¹ is hydrogen or a methyl group,R² is a linear or branched alkyl group containing 2 to 6 carbon atoms oralkylene oxides containing 4 to 21 carbon atoms andn is the number 1, 2 or 3,(A) where n is 1, R³ is an aryl group containing 6 to 18 carbon atoms, alinear or branched alkyl group containing 1 to 18 carbon atoms or acycloalkyl group containing 3 to 12 carbon atoms;(B) where n=2, R³ is[—Q—NH—C(═O)]₂[—O—R⁴—O—R⁴—C(═O)—NH—Q′—NH—C(═O))_(m)—O—R⁴—O—]in which m=0 to 10 andR⁴ is

-   -   a) a polycaprolactone diol residue,    -   b) a polytetrahydrofurfuryl diol residue or    -   c) a diol residue which is derived from a polyester diol and has        a molecular weight of 1,000 to 20,000, or        (C) where n=3, R³ is        [—Q—NH—C(═O)—O—((CH₂)₅—C(═O))_(p)—]₃R⁵,        in which R⁵ is a triol residue of a C₃₋₆ linear or branched        trihydric alcohol and        p is a number of 1 to 10 and        Q and Q′ independently of one another are C₆₋₁₈ aromatic,        aliphatic or cycloaliphatic groups derived from diisocyanates or        diisocyanate mixtures.

Examples of suitable aromatic polyisocyanates are any isomers of toluenediisocyanate (TDI) either in pure isomer form or in the form of amixture of several isomers, naphthalene-1,5-diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-2,4′-diisocyanate andmixtures of 4,4′-diphenylmethane diisocyanate with the 2,4′-isomer ormixtures thereof with higher oligomers (so-called crude MDI), xylylenediisocyanate (XDI), 4,4′-diphenyl-dimethylmethane diisocyanate, di- andtetraalkyldiphenylmethane diisocyanate, 4,4′-dibenzyldiisocyanate,1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate. Examples ofsuitable cycloaliphatic polyisocyanates are the hydrogenation productsof the above-mentioned aromatic diisocyanates such as, for example,4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI),1-isocyanatomethyl-3-isocyanato-1,5,5-trimethyl cyclohexane (isophoronediisocyanate, IPDI), cyclohexane-1,4-diisocyanate, hydrogenated xylylenediisocyanate (H₆XDI), 1-methyl-2,4-diisocyanatocyclohexane, m- orp-tetramethyl xylene diisocyanate (m-TMXDI, p-TMXDI) and dimer fattyacid diisocyanate. Examples of aliphatic polyisocyanates aretetramethoxybutan-1,4-diisocyanate, butane-1,4-diisocyanate,hexane-1,6-diisocyanate (HDI), 1,6-diisocyanato-2,2,4-trimethylhexane,1,6-diisocyanato-2,4,4-trimethylhexane, butane-1,4-diisocyanate and1,12-dodecane diisocyanate (C₁₂DI).

Suitable epoxy resin constituents for the olefinically unsaturatedcomonomers containing at least two olefinically unsaturated double bondsper molecule are any of a number of polyepoxy compounds containing atleast two 1,2-epoxy groups per molecule. The epoxy equivalent of thesepolyepoxy compounds may vary between 150 and 4,000. Basically, thepolyepoxy compounds may be saturated, unsaturated, cyclic or acyclic,aliphatic, alicyclic, aromatic or heterocyclic polyepoxy compounds.Examples of suitable polyepoxy compounds include the polyglycidyl ethersobtained by reaction of epichlorohydrin or epibromohydrin with apolyphenol in the presence of alkali. Polyphenols suitable for thispurpose are, for example, resorcinol, pyrocatechol, hydroquinone,bisphenol A (bis(4-hydroxyphenyl)-2,2-propane), bisphenol F(bis-(4-hydroxyphenyl)-methane), bis-(4-hydroxyphenyl)-1,1-isobutane,4,4′-dihydroxybenzophenone, bis-(4-hydroxyphenyl)-1,1-ethane,1,5-hydroxynaphthalene. Other basically suitable polyepoxides are thepolyglycidyl ethers of polyalcohols or diamines. These polglycidylethers are derived from polyalcohols, such as ethylene glycol,diethylene glycol, triethylene glycol, 1,2-propylene glycol,1,4-butylene glycol, triethylene glycol, pentane-1,5-diol,hexane-1,6-diol or trimethylol propane. Other polyepoxides arepolyglycidyl esters of polycarboxylic acids, for example reactions ofglycidol or epichlorohydrin with aliphatic or aromatic polycarboxylicacids, such as oxalic acid, succinic acid, glutaric acid, terephthalicacid or dimer fatty acid. Other epoxy compounds are derived from theepoxidation products of olefinically unsaturated cycloaliphaticcompounds.

Specific examples of di-, tri- or polyfunctional (meth)acrylatessuitable for use in accordance with the invention are the followingcompounds: 1,3-butyleneglycol di(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol-A-epoxidedi(meth)acrylate, alkoxylated bisphenol-A-di(meth)acrylate,polyalkyleneglykol di(meth)acrylate, trialkyleneglycol diacrylate,tetraalkyleneglycol di(meth)acrylate, neopentylglycol di(meth)acrylate,alkoxylated neopentylglykol di(meth)acrylate, trialkylolalkanetri(meth)acrylate, alkoxylated trialkylolalkane tri(meth)acrylate,glycerol alkoxytri(meth)acrylate, pentaerythritol tri(meth)acrylate,tris-(2-hydroxyalkyl)isocyanurate tri(meth)acrylate,acid-group-containing tri(meth)acrylate compounds, trimethylolpropanetri(meth)acrylate, trisalkoxy trimethylolpropane tri(meth)acrylate,ditrimethylolpropane tetra(meth)acrylate, pentaerythritoltetra(meth)acrylate, alkoxylated pentaerythritol tetra(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, “alkylene” standing for ethylene, propylene orbutylene and “alkoxy” for ethoxy, 1,2- or 1,3-propoxy or 1,4-butoxy.

The following (meth)acrylate monomers may also be used: amine-modifiedpolyether acrylate oligomers, carboxyfunctionalized multifunctional(meth)acrylates, multifunctional melamine acrylates, difunctionalsilicone acrylates.

The following (meth)acrylates may be used as monofunctional comonomers:n-/iso-alkyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-tert.-Butylcyclohexyl (meth)acrylate, dihydrodicyclopentadienyl (meth)acrylate,tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate (IBOA),β-carboxyethyl (meth)acrylate (β-CEA); mono(meth)acryloylalkylphthalates, -succinate, -maleate; 2-(2-ethoxyethoxy)-ethyl(meth)acrylate, 2-phenoxyalkyl (meth)acrylate, alkanediolmono(meth)acrylate, allyl (meth)acrylate, hydroxyalkyl (meth)acrylate,2,3-epoxyalkyl (meth)acrylate, N,N-dialkylaminoalkyl (meth)acrylate,N,N-dialkyl (meth)acrylamide, monoalkoxy trialkyleneglycol(meth)acrylat, monoalkoxy neopentylglycol alkyloxylate (meth)acrylate,polyalkylene glycol (meth)acrylate, alkoxylated nonylphenol(meth)acrylate, the alkyl groups containing 1 to 12 carbon atoms and“alkoxy” standing for ethoxy, 1,2- or 1,3-propoxy or 1,4-butoxy.

The compositions according to the invention are preferably cured by a UVor electron-beam curing process. This curing process may take place byradical or cationic polymerization according to the initiators andmonomers used.

Suitable initiators for this radical or cationic polymerization are, forexample, the following initiators: 1-hydroxycyclohexyl phenylketone,(η-5,2,4-cyclopentadien-1-yl)-[(1,2,3,4,5,6-η)-(1-methylethyl)benzene]iron(1+)-hexafluorophosphate(1−),2-benzyldimethylamino-1-(4-morpholinophenyl)-1-butanone,benzildimethylketal dimethoxyphenyl acetophenone,bis(η5-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]-titanium,bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BAPO2),2-methyl-1-[4-(methylthio)-phenyl]-2-morpholino-1-propanone,1-(4-(1-methylethyl)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one,2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenylethane-1,2-dione,1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one,(2,4,6-trimethylbenzoyl)-diphenylphosphine-oxide, α-hydroxybenzylphenylketone, triarylsulfonium-hexafluoroantimonate salts,triarylsulfonium hexafluorophosphate salts,oligo-(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone),1-propanone,2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]-homopolymer, phosphonicacid benzoyl-bis(2,6-dimethylphenyl)ester, benzophenone,methyl-ortho-benzoyl benzoate, methylbenzoylformate, 2,2-diethoxyacetophenone, 2,2-di-sec-butoxyacetophenone,[4-(4-methyl-phenylthio)phenyl]phenylmethanone-4-benzoyl-4′-methyldiphenylsulfide,p-phenylbenzophenone, 2-isopropylthioxanthone, 2-methyl anthraquinone,2-ethyl anthraquinone, 2-chloroanthraquinone, 1,2-benzanthraquinone,2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, benzil, benzoin,benzoin methylether, benzoin ethylether, benzoin isopropylether,α-methylbenzoin, α-phenylbenzoin, Michler's ketone, benzophenone,4,4′-bis-(diethylamino)benzophenone, acetophenone, diethoxyphenylacetophenone, thioxanthone, diethyl thioxanthone, 1,5-acetonaphthalene,ethyl-p-dimethyl aminobenzoate, benzilketones, 2,4,6-trimethylbenzoyldiphenyl phosphine oxides,benzilketal-(2,2-dimethoxy-1,2-diphenylethanone), 1-hydroxycyclohexylphenylketone, 2-methyl-1[4-(methylthio)phenyl]-2-morpholino-1-propanoneand/or 2-hydroxy-2-methyl-1-phenyl-1-propane and/or mixtures thereof.These initiators may optionally be combined with other radicalinitiators of the peroxide or azo type and/or with aminic accelerators.

Although cationic polymerization is preferably used, vinyl ethers mayalso be employed as comonomers. Examples of such vinyl ethers arevinylmethylether, vinylethylether, vinylpropylether, vinylisobutylether,vinyidodecylether, vinyloctadecylether, vinylcyclohexylether,vinyl-4-hydroxybutylether, butanediol-1,4-divinylether, 1,4-cyclohexanedimethanol divinylether, diethyleneglycol divinylether,triethyleneglycol divinylether and the following vinyl compounds:N-vinylpyrrolidone, vinylcaprolactam, 1-vinylimidazole, divinylethyleneurea.

The principal components of the compositions according to the inventionare used in the following quantities:

-   a) 1 to 80% by weight, preferably 1 to 40% by weight, of    organotitanium, organosilicon and/or organozirconium compound    corresponding to formula (I),-   b) 20 to 95% by weight, preferably 40 to 90% by weight, of comonomer    containing at least 2 double bonds per molecule,-   c) 0 to 40% by weight of comonomer containing 1 double bond per    molecule,-   d) 0.1 to 10% by weight of an initiator or a mixture of initiators,-   e) 0 to 30% by weight other additives and auxiliaries.

It is well known to the expert that the components mentioned above,particularly the organometallic compounds, can enter into reactions withone another and, as technical products, can contain impurities so thatthey are present in the treatment composition in the form whichcorresponds to the thermodynamic or kinetic equilibrium under theconditions mentioned.

The compositions according to the invention may contain as furtheradditives conductivity pigments or conductive fillers such as, forexample, iron phosphide (Ferrophos), vanadium carbide, titanium nitride,carbon black, graphite, molybdenum sulfide or tin- or antimony-dopedbarium sulfate. Iron phosphide is particularly preferred. Theconductivity pigments or fillers are added to improve weldability or toimprove coating with electrodeposition paints. These inorganicauxiliaries should be present in fine-particle form, i.e. their meanparticle diameters are between 0.005 and 5 μm and preferably between0.05 and 2.5 μm. The auxiliaries are used in quantities of 0 to 30% byweight.

The compositions may also contain additives for improving formingbehavior, for example wax-based derivatives based on natural orsynthetic waxes, for example polyethylene, polytetrafluoroethylene(PTFE) or wax derivatives.

Where it is used on metal strip surfaces in particular, the compositionis applied in known manner to an optionally metal-coated steel strip or(alloyed) aluminium strip by chemcoating, stripping, by the curtain flowprocess, by immersion/squeezing or spraying/squeezing at temperatures of10 to 50° C. and preferably in the range from 15 to 35° C.

The compositions according to the invention are preferably cured orcrosslinked by ultraviolet (UV) radiation or by electron beam. SuitableUV radiation has wavelengths of 200 to 800 nm and preferably in therange from 250 to 450 nm. The radiation intensity is determined by thedesired application rate, the initiator system and the comonomercomposition and may readily be determined by the expert. The electronbeam alternatively used may be generated by any conventional electronbeam source, for example by an accelerator of the van de Graaffgenerator, linear accelerator, resonance transformer or dynatron type.The electron beam has an energy of ca. 50 to 1,000 keV and preferably inthe range from 100 to ca. 300 keV. The resulting radiation dose is inthe range from ca. 0.1 to 100 Mrad.

The formation of the film, the crosslinking of the film and itsanchorage on the metal surface are preferably achieved by UV radiationor by electron beam as known per se. The exposure time is between 0.1and 120 seconds and preferably between 1 and 30 seconds. The coating hasa weight per unit area after crosslinking of 0.1 to 10 and preferably0.5 to 5.0 g/m². The film forming reaction may optionally be supportedby the application of heat.

The layers thus produced may be coated with the liquid or powder-formfinishing paints typically used in the domestic appliance and/orarchitectural industries. In addition, the corrosion-inhibiting layeraccording to the invention may be immediately coated with typical stripfinishing paints. The coatings thus produced protect the plate andprovide adequate protection against corrosion to DIN 53167 and adequatesubstrate adhesion to DIN 53151. The corrosion resistance of materialstreated with the corrosion-inhibiting composition according to theinvention reaches the levels achievable with a conventional coating.

If the treatment according to the invention is carried out immediatelyafter metallic surface finishing, for example electrolytic galvanizationor hot-dip galvanization, of steel strip, the strip may be contactedwith the treatment solution or dispersion according to the inventionwithout preliminary cleaning. However, if the metal strip to be treatedhas been stored and/or transported before the treatment according to theinvention, it is generally provided with corrosion-inhibiting oils or isat least soiled to such an extent that it has to be cleaned beforecoating in accordance with the invention. Cleaning may be carried outwith conventional mildly to strongly alkaline cleaners or—in the case ofaluminium and its alloys—even with acidic cleaners.

The invention is illustrated in the following by a few Examples. Asregards the compositions, all quantities are in parts by weight unlessotherwise indicated.

The metal plates were cleaned (for 15 secs.) with a 2.5% Ridoline 72(Henkel) solution heated to 60° C. The plates were then rinsed withdeionized water and dried.

The individual components listed in Table 1 were generally processed inthe order shown by stirring at room temperature to form a homogeneousmixture.

The UV-curing formulations were then applied by knife coating. Theplates thus prepared were then cured by UV radiation until they weretack-free.

A BASF polyester finishing paint was then applied by knife coating andstoved to the manufacturer's specification.

Cross hatch test DIN 53 151 [mm] STT paint creepage Indentation CoatingDIN 53 167 With weight Score [mm] Edge a) 3 mm Example Composition[g/m²] Hours one-sided [mm] Without b) 6 mm 1 93.0% Photomer 4017(Henkel KGaA)   9.5 100 10.6 9.8 4 a) — 7.0% Initiator (mixture) b) — 267.9% Photomer 4017 (Henkel KGaA) 15  100 0.8 1.6 0 a) 1 27.0% Tiorganyl compound b) — 5.1% Initiator (mixture 3 93.0% Ebecryl 408 (ucbChemicals) 35–40 100 4.5 2.4 3 a) — 7.0% Initiator (mixture) b) — 467.9% Ebecryl 408 (ucb Chemicals) 10  100 0.5 2.4 0 a) 0 27.0% Tiorganyl compound b) 2 5.1% Initiator mixture 5 93.0% Sartomer SR 9051(Cray Valley) 6 100 1 2.7/1.4 0 a) 0 7.0% Initiator (mixture) b) 0 667.9% Sartomer SR 9051 (Cray Valley) 5 100 1.0 2.1 0 a) 0 27.0% Tiorganyl compound b) 0 5.1% Initiator (mixture) 7 93.0% Photomer 8061(Henkel KGaA) 6 100 Complete flaking 2 a) 5 7.0% Initiator (mixture) b)— 8 67.9% Photomer 8061 (Henkel KGaA) 3 100 3 2.4 0 a) 0 27.0% Tiorganyl compound b) 0 9 93.0% Photomer 4149 (Henkel KGaA) 7 100 5 3.3 0a) 5 7.0% Initiator (mixture) b) 5 10 67.9% Photomer 4149 (Henkel KGaA)5 100 0.8 2.4 0 a) 0 27.0% Ti organyl compound b) 0 5.1% Initiator(mixture) 11 93.0% Laromer PO 84 F (BASF AG) 4–5 100 8 3   5 a) 5 7.0%Initiator (mixture) b) 5 12 67.9% Laromer PO 84 F (BASF AG) 3 100 0.81.5 1 a) 1–2 27.0% Ti organyl compound b) 2 5.1% Initiator (mixture) 1393.0% Sartomer C 2000 (Cray Valley) 2–3 100 0.9 1.4 1 a) 2 7.0%Initiator (mixture) b) 2 14 67.9% Sartomer C 2000 (Cray Valley) 2 1001.6 1.7 1 a) 1 27.0% Ti organyl compound b) 1 5.1% Initiator (mixture)15 93.0% Photomer 6230 (Henkel KGaA) 35–63 Complete flaking of — a) —7.0% Initiator (mixture) the PE finishing paint b) — 16 67.9% Photomer6230 (Henkel KGaA) 3–7 100 0.3 1.2 0 a) 0 27.0% Ti organyl compound b) 15.1% Initiator (mixture)Remarks on the Results Out in the Table:

Commercially available Ti trimethacrylate methoxyethoxy ethoxide wasused as the Ti organyl compound; a mixture of 2,4,6-trimethylbenzoyldiphenyl phosphine oxide and 1-hydroxycyclohexyl phenyl ketone was usedas the initiator mixture.

Examples 2, 4, 6, 8, 10, 12, 14, 16 correspond to the invention and showa good corrosion-inhibiting effect in the salt spray test to DIN 53167and good substrate adhesion in the cross hatch adhesion test to DIN 53151 with and without indentation whereas Comparison Examples 1, 3, 5, 7,9, 13, 15 show an unsatisfactory corrosion-inhibiting effect andunsatisfactory substrate adhesion. Compositions containing titaniummethacrylate triisopropoxide, titanium methacryloxyethyl acetoacetatetriisopropoxide, (2-methacryloxyethoxy)-triisopropoxytitanate alsoproduced good results. Favorable curing rates were also achieved byusing the following initiators or initiator mixtures of benzil dimethylketal, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one.

1. A chromium-free process for inhibiting corrosion of substratescomprising steel, the process comprising the steps of: a) contacting aclean, untreated surface comprising steel with a corrosion inhibitorcomposition for 0.5 to 60 seconds at a treatment temperature of 10° C.to 50° C., said corrosion inhibitor comprising: i) one or more compoundsof formula (I):(CR¹R²═CR³—COO—)_(n)—Me—(O—X)_(4-n)  (I) in which R¹ and R² represent H,C₁₋₁₂ alkyl, aralkyl, or the group —CO—O—Y, R³ is H or C₁₋₁₂ alkyl, Meis a titanium, silicon, or zirconium ion, X is H, C₁₋₁₂ alkyl, aryl,aralkyl, alkoxyl, aroxyl, sulfonyl, phosphate, or pyrophosphate, Y is H,C₁₋₁₂ alkyl, or Me, and n=0 to 4; ii) at least one olefinicallyunsaturated co-monomer containing at least two olefinically unsaturateddouble bonds per molecule; iii) optionally, one or more otherco-monomers containing one olefinically unsaturated double bond permolecule; and iv) one or more radical or cationic polymerizationinitiators, or any combination thereof, wherein at least one initiatoris activatable by radiation; b) removing excess corrosion inhibitor, ifany, from the substrate; and c) applying a suitable supply of energy for0.1 to 120 seconds to the corrosion inhibitor to polymerize the monomersand form a polymeric film on the substrate, said polymeric film having aweight per unit area of 0.1 to 10 g/m².
 2. The process of claim 1,wherein the treatment temperature in a) is 15° C. to 35° C.
 3. Theprocess of claim 1, wherein the at least one olefinically unsaturatedco-monomer ii) containing at least two olefinically unsaturated doublebonds per molecule comprises one or more esterification products ofalkane polyols, polyester polyols, polyether polyols or polyepoxidesoptionally containing hydroxyl groups with one or more olefinicallyunsaturated carboxylic acids selected from the group consisting ofacrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleicacid, maleic acid semiester, fumaric acid, fumaric acid semiester,reactive carboxyfunctional macromonomers, and mixtures thereof.
 4. Theprocess of claim 1, wherein the olefinically unsaturated comonomer ii)comprises one or more esterification products of one or more compoundsselected from the group consisting of C₂₋₃₆ diols, polyalkylene glycoldiols, C₃₋₁₂ triols, trisalkoxylates of C₃₋₁₂ triols, polyester polyols,polyepoxy compounds, and mixtures thereof with the one or moreolefinically unsaturated carboxylic acids.
 5. The process of claim 1,wherein the olefinically unsaturated comonomer ii) comprises one or morereaction products of one or more polyurethanes containing freeisocyanate groups with one or more OH-functional alkyl (meth)acrylates.6. The process of claim 1, wherein the corrosion inhibitor comprises 1%to 80% by weight of one or more compounds of formula (I), 20% to 95% byweight of at least one other olefinically unsaturated co-monomercontaining at least two olefinically unsaturated double bonds permolecule, 0% to 40% by weight of the one or more other co-monomerscontaining one olefinically unsaturated double bond per molecule, 0.1%to 10% by weight of the one or more initiators, and 0% to 30% by weightof other additives and auxiliaries.
 7. The process of claim 1, whereinthe corrosion inhibitor comprises 1% to 40% by weight of one or morecompounds of formula (I) and 40% to 90% by weight of at least one otherolefinically unsaturated co-monomer containing at least two olefinicallyunsaturated double bonds per molecule.
 8. A chromium-free process forinhibiting corrosion of substrates comprising steel, the processcomprising the steps of: a) applying a corrosion inhibitor compositiondirectly to a clean, unphosphated steel surface for 0.5 to 60 seconds ata treatment temperature of 10° C. to 50° C., said corrosion inhibitorcomprising: i) one or more compounds of formula (I):(CR¹R²═CR³—COO—)_(n)—Me—(O—X)_(4-n)  (I) in which R¹ and R² represent H,C₁₋₁₂ alkyl, aralkyl, or the group —CO—O—Y, R³ is H or C₁₋₁₂ alkyl, Meis a titanium, silicon, or zirconium ion, X is H, C₁₋₁₂ alkyl, aryl,aralkyl, alkoxyl, aroxyl, sulfonyl, phosphate, or pyrophosphate, Y is H,C₁₋₁₂ alkyl, or Me, and n=0 to 4; ii) at least one olefinicallyunsaturated co-monomer containing at least two olefinically unsaturateddouble bonds per molecule; iii) optionally, one or more otherco-monomers containing one olefinically unsaturated double bond permolecule; and iv) one or more radical or cationic polymerizationinitiators, or any combination thereof, wherein at least one initiatoris activatable by radiation; b) removing excess corrosion inhibitor, ifany, from the unphosphated steel surface; and c) applying a suitablesupply of energy for 0.1 to 120 seconds to the corrosion inhibitor topolymerize the monomers and form a corrosion inhibiting film on theunphosphated steel surface, said corrosion inhibiting film having aweight per unit area of 0.1 to 10 g/m².
 9. The chromium-free process ofclaim 8 wherein Me is titanium.
 10. A chromium-free process forinhibiting corrosion of substrates comprising steel, the processcomprising the steps of: a) applying a corrosion inhibitor compositiondirectly to a clean, unphosphated metal surface, said surface beingaluminum, alloys of aluminum or steel, said steel optionally providedwith a metallic coating of zinc, aluminum, copper or nickel, or anycombination thereof, for 0.5 to 60 seconds at a treatment temperature of10° C. to 50° C., said corrosion inhibitor comprising: i) one or morecompounds of formula (I):(CR¹R²═CR³—COO—)_(n)—Me—(O—X)_(4-n)  (I) in which R¹ and R² represent H,C₁₋₁₂ alkyl, aralkyl, or the group —CO—O—Y, R³ is H or C₁₋₁₂ alkyl, Meis a titanium, silicon, or zirconium ion, X is H, C₁₋₁₂ alkyl, aryl,aralkyl, alkoxyl, aroxyl, sulfonyl, phosphate, or pyrophosphate, Y is H,C₁₋₁₂ alkyl, or Me, and n=0 to 4; ii) at least one olefinicallyunsaturated co-monomer containing at least two olefinically unsaturateddouble bonds per molecule; iii) optionally, one or more other comonomerscontaining one olefinically unsaturated double bond per molecule; andiv) one or more radical or cationic polymerization initiators, or anycombination thereof, wherein at least one initiator is activatable byradiation; b) removing excess corrosion inhibitor, if any, from theunphosphated steel surface; and c) applying a suitable supply of energyfor 0.1 to 120 seconds to the corrosion inhibitor to polymerize themonomers and form a corrosion inhibiting film on the unphosphated steelsurface, said corrosion inhibiting film having a weight per unit area of0.1 to 10 g/m².